Thermoplastic composites comprising water-soluble peo graft polymers for use as a sacrificial support in 3d additive manufacturing

ABSTRACT

A method for preparing a vapor sensitive sacrificial support material. The method may include decomposing a polycondensed PEO polymer with heat in the presence of a graphene-like material to release PEO polymer radicals from the polycondensed PEO polymer, such that at least a portion of the PEO polymer radicals become trapped on at least a portion of a surface of the graphene-like material to form a coated graphene-like material, which may be defined as a structural reinforcement material. The method may further include forming the vapor sensitive water-soluble thermoplastic polyethylene oxide graft polymer. The vapor sensitive water-soluble thermoplastic polyethylene oxide graft polymer may include a polyethylene oxide polymer backbone. The vapor sensitive water-soluble thermoplastic polyethylene oxide graft polymer may further include one or more nanoscopic particulate processing aids. The structural reinforcement material may be uniformly dispersed in the vapor sensitive water-soluble thermoplastic polymer composite.

RELATED APPLICATIONS

This application is a continuation application of and claims priority under 35 U.S.C. § 120 of U.S. patent application Ser. No. 17/406,818, now U.S. Pat. No. 11,685,124, issued Jun. 27, 2023 (Attorney Docket No. 4460.00020) filed on Aug. 19, 2021 and titled THERMOPLASTIC COMPOSITES COMPRISING WATER-SOLUBLE PEO GRAFT POLYMERS FOR USE AS A SACRIFICIAL SUPPORT IN 3D ADDITIVE MANUFACTURING, which in turn is a continuation application of and claims priority under 35 U.S.C. § 120 of U.S. patent application Ser. No. 15/555,253, now U.S. Pat. No. 11,097,492, issued Aug. 24, 2021 (Attorney Docket No. 4460.00004) filed on Sep. 1, 2017 and titled Thermoplastic Composites Comprising Water-Soluble PEO Graft Polymers Useful For 3-Dimensional Additive Manufacturing, which in turn is a national phase application of and claims priority under 35 U.S.C. § 371 of PCT Patent Application Serial No. PCT/US16/020031 filed on Feb. 29, 2016 and titled Thermoplastic Composites Comprising Water-Soluble PEO Graft Polymers Useful For 3-Dimensional Additive Manufacturing, which in turn claims priority under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No. 62/126,962 filed on Mar. 2, 2015 and titled Thermoplastic Composites Comprising Water-Soluble PEO Graft Polymers Useful For 3-Dimensional Additive Manufacturing. The contents of these applications are incorporated herein by reference except for where they conflict with the disclosures herein.

FIELD OF THE INVENTION

The present invention relates to water-soluble thermoplastic polymer composites comprising water-soluble polyethylene oxide graft polymers, and nanoscopic particulate processing aids such as titanium dioxide nanopowders. The present invention also relates to water-soluble thermoplastic polymer composites comprising water-soluble polyethylene oxide graft polymers, structural reinforcement materials such as carbon or glass fibers, and plasticizers. The present invention further relates to the use of these water-soluble thermoplastic polymer composites in preparing, for example, three-dimensional (3D) water-soluble prototypes, models, in casting molds for designing and printing three-dimensional (3D) articles that may require some sacrificial support material, in constructing customized biological scaffolds for bone and tissue regeneration, as well as for constructing printable vapor sensors.

BACKGROUND OF THE INVENTION

Prototypes of objects, parts, molds, etc., may be used worldwide in a wide variety of technologies such as aerospace, automotive, pharmaceutical, biomedical, etc. Many different methods and strategies are also employed in such prototype manufacturing. For example, a prototype may be sculpted from a bulk material. In such cases, the prototype may be drawn manually of with the aid of computer-assisted software, and then machined or carved manually by removing extra material from a bulk piece. Such processing may require multiple iterations until a satisfactory prototype may be produced. Another approach would be to create a mold of the desired object, and then make a prototype of the object by filling the mold with the desired material, followed by processing or curing using an appropriate technique that would allow for the solid object to be produced. Multiple iterations may also be needed to create a successful mold for such object. Accordingly, both sculpting and molding of the prototype may be time-consuming and costly.

Another method for creating a prototype may be by so called “free-forming” where the formation of the three-dimensional object is achieved by sequentially depositing multiple layers of the fluid material onto a base. The fluid then solidifies layer-by-layer and determines the prototype shape. See, for example, U.S. Pat. No. 5,340,433 (Crump), issued Aug. 23, 1994, and U.S. Pat. No. 5,121,329 (Crump), issued Jun. 9, 1992, which describes one such method. In this method certain types of materials, such as waxes, are dispensed in such way that, upon solidification of the preceding layer, another layer of material is deposited on top of the solidified preceding layer. While seemingly convenient and lower cost, such methods may have restrictions in terms of the types of materials that may be processed. For example, lower melting viscosity waxes and certain thermosets may be employed in such methods, but the quality of the prototypes produced may not be optimal.

This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.

SUMMARY OF THE INVENTION

With the above in mind, embodiments of the present invention are related to a method for preparing a vapor sensitive sacrificial support material. The method may include decomposing a polycondensed PEO polymer with heat in the presence of a graphene-like material to release PEO polymer radicals from the polycondensed PEO polymer, such that at least a portion of the PEO polymer radicals become trapped on at least a portion of a surface of the graphene-like material to form a coated graphene-like material, which may be defined as a structural reinforcement material. The method may further include forming the vapor sensitive water-soluble thermoplastic polyethylene oxide graft polymer.

The vapor sensitive water-soluble thermoplastic polyethylene oxide graft polymer may include a polyethylene oxide polymer backbone, and include from about 0.05% to about 10% by weight of the polyethylene oxide polymer backbone of at least one polar vinyl monomer grafted to the polyethylene oxide polymer backbone. The vapor sensitive water-soluble thermoplastic polyethylene oxide graft polymer may further include one or more nanoscopic particulate processing aids that may be uniformly dispersed in the graft polymer in an amount of from about 0.05 to about 10% by weight of the vapor sensitive water-soluble thermoplastic polymer composite. The structural reinforcement material may be uniformly dispersed in the vapor sensitive water-soluble thermoplastic polymer composite in an amount of from about 0.1 to about 20% by weight of the vapor sensitive water-soluble thermoplastic polymer composite.

The vapor sensitive water-soluble thermoplastic polymer composite may be formable into a 3D printable sacrificial support material. The vapor sensitive water-soluble thermoplastic polyethylene oxide graft polymer composite may have a viscosity in the range of about 100 to about 10,000 Pa-sec. when measured at a shear rate in the range of about 1×101 to about 1×104 reciprocal seconds. Water-soluble may be defined as at least one of a composite, composition, substance, and material that is soluble in that it melts, liquefies, dissolves, disintegrates, falls apart, or solubilizes when brought into contact with an aqueous fluid. The vapor sensitive water-soluble thermoplastic polymer composite may have an initial electrical resistance value that increases when the vapor sensitive water-soluble thermoplastic polymer composite is exposed to solvent vapor.

The solvent vapor may include dichloromethane, chloroform, tetrahydrofuran, carbon tetrachloride, acetonitrile, alcohols, and/or cyclohexane. The electrical resistance of the vapor sensitive water-soluble thermoplastic polymer composite may return to the initial electrical resistance value when the vapor sensitive water-soluble thermoplastic polymer composite is exposed to dry air. The 3D printable sacrificial support material may be in the form of a filament, film, powder, pellet, or suspended in solvent. The graphene-like material may comprise graphene, graphene nanoplatelets, graphene oxide, graphite, functionalized graphene nanoplatelets, plasma treated graphene nanoplatelets; reduced graphene oxide, partially reduced graphene oxide, carbon fibers, carbon nanotubes, and/or carbon black.

The catalytic thermal initiator may comprise 4,4′-azobis (4-cyanopentanoyl dichloride), alkyl, dialkyl, diaryl, arylalkyl peroxides, di-t-butyl peroxide, cumyl peroxide, 1,1-di-t-butylperoxy, hexane, acyl peroxide, acetyl peroxide, benzoyl peroxide, hydroperoxide, cumyl hydroperoxide, p-methane hydroperoxide, perester, peroxyester, t-butyl peroxypivalate, t-butyl perbenzoateetc, alkylsulfonyl peroxide, dialkyl peroxymonocarbonate, dialkyl peroxycarbonate, ketone peroxide, azo compound, 2,2′-azobisisobutyronitrile (AIBN), and/or 1,1′-azobis (cyclohexanecarbonitrile). The 3D printable sacrificial support material may comprise a filament for a fused filament fabrication (FFF) technique, a powder or pellet for a selective laser sintering (SLS) technique, is suspended in a solvent for an inkjet 3D printing technique, and/or a pellet, powder, or crushed for an injection molding 3D printing technique.

The one or more nanoscopic particulate processing aids may comprise titanium dioxide nanopowder, alumina nanopowder, silica nanopowder, fumed silica, zirconia nanopowder, vanadia nanopowder, antimony oxide nanopowder, tin oxide nanopowder, ceria nanopowder, and/or zinc oxide nanopowder. The vapor sensitive water-soluble thermoplastic polymer composite may include a plasticizer that may be in an amount of from about 0.1 to about 10% by weight of the vapor sensitive water-soluble thermoplastic polymer composite.

Embodiments of the present invention may be related to a 3D printable sacrificial support material for use in printing a 3D article, the 3D printable sacrificial support material. The 3D printable sacrificial support material may include a vapor sensitive water-soluble thermoplastic polymer composite. The vapor sensitive water-soluble thermoplastic polymer composite may comprise a vapor sensitive water-soluble thermoplastic polyethylene oxide graft polymer that may have a polyethylene oxide polymer backbone and from about 0.05% to about 10% by weight of the polyethylene oxide polymer backbone of at least one polar vinyl monomer grafted to the polyethylene oxide polymer backbone.

The vapor sensitive water-soluble thermoplastic polymer composite may further comprise one or more nanoscopic particulate processing aids that may be uniformly dispersed in the graft polymer in an amount of from about 0.05 to about 10% by weight of the vapor sensitive water-soluble thermoplastic polymer composite. The vapor sensitive water-soluble thermoplastic polymer composite may yet further comprise a plasticizer that may be in an amount of from about 0.1 to about 10% by weight of the vapor sensitive water-soluble thermoplastic polymer composite. The vapor sensitive water-soluble thermoplastic polymer composite may also comprise a structural reinforcement material that may be uniformly dispersed in the vapor sensitive water-soluble thermoplastic polymer composite that may be in an amount of from about 0.1 to about 20% by weight of the vapor sensitive water-soluble thermoplastic polymer composite.

The structural reinforcement material may comprise a graphene-like material that may include polycondensed polyethylene oxide polymer radicals carried on at least a portion of a surface of the graphene-like material. The vapor sensitive water-soluble thermoplastic polymer composite may have an initial electrical resistance value that increases when the vapor sensitive water-soluble thermoplastic polymer composite is exposed to solvent vapor. The electrical resistance of the vapor sensitive water-soluble thermoplastic polymer composite may return to the initial electrical resistance value when the vapor sensitive water-soluble thermoplastic polymer composite is exposed to dry air. Water-soluble may be defined as at least one of a composite, composition, substance, and material that is soluble in that it melts, liquefies, dissolves, disintegrates, falls apart, or solubilizes when brought into contact with an aqueous fluid.

The vapor sensitive water-soluble thermoplastic polymer composite may have a viscosity in the range of about 100 to about 10,000 Pa-sec. when measured at a shear rate in the range of about 1×101 to about 1×104 reciprocal seconds. The solvent vapor may comprise at least one of dichloromethane, chloroform, tetrahydrofuran, carbon tetrachloride, acetonitrile, alcohols, and cyclohexane. The 3D printable sacrificial support material may be in the form of a filament, film, powder, pellet, or suspended in solvent.

The graphene-like material may comprise graphene, graphene nanoplatelets, graphene oxide, graphite, functionalized graphene nanoplatelets, plasma treated graphene nanoplatelets; reduced graphene oxide, partially reduced graphene oxide, carbon fibers, carbon nanotubes, and/or carbon black. The 3D printable sacrificial support material may comprise a filament for a fused filament fabrication (FFF) technique, a powder or pellet for a selective laser sintering (SLS) technique, is suspended in a solvent for an inkjet 3D printing technique, and/or a pellet, powder, or crushed for an injection molding 3D printing technique. The nanoscopic particulate processing aids may comprise titanium dioxide nanopowder, alumina nanopowder, silica nanopowder, fumed silica, zirconia nanopowder, vanadia nanopowder, antimony oxide nanopowder, tin oxide nanopowder, ceria nanopowder, and/or zinc oxide nanopowder.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the present invention are illustrated as an example and are not limited by the figures of the accompanying drawings, in which like references may indicate similar elements.

FIG. 1 is a graphical plot of melt viscosity versus shear rate for polyethylene oxide (PEO) polymer (WSR 303, approximate molecular weight of 7,000,000 g./mol.) as neat polymer, as a PEO polymer having grafted thereon 5% 2-hydroxyethyl methacrylate (HEMA), as well as the PEO HEMA grafted polymer to which is added a plasticizer (i.e., poly(ethylene glycol) dimethylether) and a nanoscopic particulate titanium dioxide processing aid to form a polymer composite; and

FIG. 2 is graphical plot of melt viscosity versus temperature of the grafted PEO HEMA grafted polymer only of FIG. 1 , as well as the PEO HEMA grafted polymer to which is added the plasticizer and the nanoscopic particulate titanium dioxide processing aid of FIG. 1 to form a polymer composite.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Those of ordinary skill in the art realize that the following descriptions of the embodiments of the present invention are illustrative and are not intended to be limiting in any way. Other embodiments of the present invention will readily suggest themselves to such skilled persons having the benefit of this disclosure. Like numbers refer to like elements throughout.

Although the following detailed description contains many specifics for the purposes of illustration, anyone of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention. Accordingly, the following embodiments of the invention are set forth without any loss of generality to, and without imposing limitations upon, the claimed invention.

In this detailed description of the present invention, a person skilled in the art should note that directional terms, such as “above,” “below,” “upper,” “lower,” and other like terms are used for the convenience of the reader in reference to the drawings. Also, a person skilled in the art should notice this description may contain other terminology to convey position, orientation, and direction without departing from the principles of the present invention.

Furthermore, in this detailed description, a person skilled in the art should note that quantitative qualifying terms such as “generally,” “substantially,” “mostly,” and other terms are used, in general, to mean that the referred to object, characteristic, or quality constitutes a majority of the subject of the reference. The meaning of any of these terms is dependent upon the context within which it is used, and the meaning may be expressly modified.

It is advantageous to define several terms before describing the invention. It should be appreciated that the following definitions are used throughout this application.

Definitions

Where the definition of terms departs from the commonly used meaning of the term, applicant intends to utilize the definitions provided below, unless specifically indicated.

For the purposes of the present invention, the term “water-soluble” refers to a composite, composition, substance, material, etc., which is soluble, or substantially soluble (e.g., melts, liquefies, dissolves, disintegrates, falls apart, solubilizes, etc.) when brought into contact with an aqueous fluid (e.g., water), for example, at ambient temperatures (e.g., room temperature, environmental temperature, etc.).

For the purposes of the present invention, the term “thermoplastic” refers to the conventional meaning of thermoplastic, i.e., a composition, compound, material, etc., that exhibits the property of a material, such as a high polymer, that softens or melts so as to become pliable, malleable, etc., when exposed to sufficient heat and generally returns to its original condition when cooled to room temperature.

For the purposes of the present invention, the term “polymer composite” refers to a composition comprising a water-soluble polyethylene oxide (PEO) graft polymer which provides the external or continuous (bulk) phase and in which is dispersed one or more other materials, substances, processing aids, etc., such as nanoscopic particulate processing aids, plasticizers, structural reinforcement materials, etc.

For the purposes of the present invention, the term “substantially uniformly dispersed” refers to a dispersion of a material, substance, compound, etc., in the bulk (continuous) phase (e.g., graft polymer) such that the bulk phase is substantially uniform in terms of composition, texture, characteristics, properties, etc.

For the purposes of the present invention, the term “graft polymer” refers to a copolymer comprised of a main polymer backbone which is modified by side chains of one or more polymerized monomers covalently bonded to (grafted on) the polymer backbone.

For the purposes of the present invention, the term “polyethylene oxide (PEO) graft polymer” (hereafter referred to interchangeably as “PEO graft polymer”) refers to a copolymer comprised of a main polyethylene oxide (PEO) polymer backbone which is modified by side chains of one or more polymerized polar vinyl monomers covalently bonded to (grafted on) the polyethylene oxide (PEO) polymer backbone.

For the purposes of the present invention, the term “polyethylene oxide (PEO) polymer” (hereafter referred to interchangeably as “PEO polymer”) refers to a water-soluble polyether polymer (also called poly(ethylene glycol) or poly(oxyethylene)) having an approximate molecular weight at least about 4,000,000 g/mol., for example, in the range of from about 4,000,000 to about 8,000,000 g/mol., such as from about 6,750,000 to about 7,250,000 g/mol. Suitable PEO polymers for use herein may include one or more of: Dow Chemical POLYOX water-soluble PEO resins such as WSR-303, WSR-308, WSR Coagulant, UCARFLOC Polymer 300, ULCARFLOC Polymer 302, ULCARFLOC Polymer 304, UCARFLOC Polymer 309, etc.; Sigma-Aldrich grades 189464, 189472 and 372838; etc.

For the purposes of the present invention, the term “polar vinyl monomer” refers to any ethylenically unsaturated monomers having polar functional groups (e.g., hydroxy, hydroxyalkyl, polyether, carboxyl, amino, carbonyl, halo, thiol, sulfonic, sulfonate, etc.) which may be grafted onto a PEO polymer backbone, such as, for example, hydroxyalkylacrylates, polyetheracrylates (e.g., poly(ethylene glycol) acrylates), hydroxyalkylmethacrylates, polyethermethacrylates, (e.g., poly(ethylene glycol)methacrylates), vinyl acetate, acrylonitrile, etc. Suitable polar vinyl monomers for use herein may include one or more of: 2-hydroxyethyl methacrylate (HEMA); poly(ethylene glycol)methacrylate (PEG-MA); etc.

For the purposes of the present invention, the term “approximate molecular weight” refers to the approximate weight (in grams) of one mole of the PEO polymer molecules, based upon melt rheology measurements.

For the purposes of the present invention, the term “melt strength” refers to the resistance of the melted polymer composite to stretching and reflect how strong polymer composite is when in a molten state. Melt strength of the melted polymer composite is related to the molecular chain entanglements of the polymer in the composite and its resistance to untangling under strain. The polymer properties affecting such resistance to untangling include, for example, molecular weight, molecular-weight distribution (MWD), molecular branching, etc. As each of these properties increase, melt strength of the polymer may be improved at lower shear rates.

For the purposes of the present invention, the term “melt viscosity” refers to dynamic viscosity of the melted (e.g., molten) material as measured by a rheometer (e.g., a Discovery Hybrid Rheometer (DHR-2) made by TA Instruments), and depends upon the shear rate. For example, at higher shear rates, the melt viscosity of a material may be determined in an oscillation experiment by applying the Cox-Merz rule (see W. P. Cox, and E. H. Merz, J. Polymer Science, 28:619 (1958).

For the purposes of the present invention, the term “viscoelasticity” and “elastic viscosity” refer interchangeably to the property of materials which exhibit both viscous and elastic characteristics when undergoing deformation. Viscous materials resist shear flow and strain linearly with time when a stress is applied, while elastic materials strain instantaneously when stretched and just as quickly return to their original state once the stress is removed. Viscoelastic materials have elements of both of these properties and, as such, exhibit time dependent strain. Whereas elasticity is usually the result of bond stretching along crystallographic planes in an ordered solid, viscoelasticity is the result of the diffusion of atoms or molecules inside of a material.

For the purposes of the present invention, the term “shear rate” refers to rate at which a progressive shearing deformation is applied to a material (as measured by a rheometer) and is defined in units of reciprocal seconds (1/sec.).

For the purposes of the present invention, “plasticizer” refers to the conventional meaning of this term as an agent which, for example, softens, makes more flexible, malleable, pliable, plastic, etc., a polymer, thus providing flexibility, pliability, durability, etc., which may also decrease the melting and the glass transition temperature of the polymer, and which may include, for example, one or more of: poly(ethylene glycol) dimethyl ether (PEGM); triethyl citrate; triacetin, propylene glycol; dibutyl sebacate; glycerol monostearate; diethyl phthalate; crown ethers (e.g., crown ethers formed from oligomers of ethylene oxide); poly(ethylene glycol) dimethylether; etc.

For the purposes of the present invention, the term “nanoscopic particulate processing aids” refers to nanoscopic particulate additives (e.g., nanoparticles, nanopowders, etc.) which alter the melt processability and handling properties (e.g., altering viscosity properties, etc.) of the polymer composite. Nanoscopic particulate processing aids useful herein may include nanoscopic particulates comprising, for example, one or more of: titanium dioxides (TiO.sub.2); aluminum oxides (Al.sub.2O.sub.3), silicon oxides (SiO.sub.2); fumed silica; other metal oxides such as zirconia, vanadia, chromia, antimony oxide, tin oxide, ceria, zinc oxide, etc., surface-modified nanoscopic particulates; etc.

For the purposes of the present invention, the term “structural reinforcement materials” refers to additives which may alter structural integrity and/or strength of the polymer. Structural reinforcement materials useful herein may include, for example, one or more of: carbon fibers; carbon nanotubes; glass fibers; metal or metal oxide fibers; clay; talc; chalk; boron nitride; magnesium hydroxide, magnesium carbonate, diatomaceous earth; mica; glass quartz; ceramic and/or glass microbeads or spheres; graphene; graphene nanoplatelets; graphene oxide; reduced graphene oxide, graphite; carbon black; other graphene-like materials; etc.

For the purposes of the present invention, the term “nanoscopic” refers to materials, substances, structures, etc., having a size in at least one dimension (e.g., thickness) of from about 1 to about 1000 nanometers, such as from about 1 to about 100 nanometers. Nanoscopic materials, substances, structures, etc., may include, for example, nanoparticles; nanopowders; nanoplatelets, nanofibers, nanotubes, nanowhiskers, etc.

For the purposes of the present invention, the term “carbon material” material refers to materials made of carbon. Carbon materials may include one or more of: graphite; graphite flakes; carbon black; graphene; graphene-like materials; (e.g., reduced graphene oxide, functionalized graphene, graphene oxide, partially reduced graphene oxide, etc.); carbon-based nanofibers; carbon-based nanotubes; etc.

For the purposes of the present invention, the term “graphene-like material” refers to a material, substance, etc., which may have a layered structure the same or similar to graphene. Graphene-like materials may include one or more of: graphene; graphene nanoplatelets; functionalized graphene; graphene oxide; reduced graphene oxide; partially reduced graphene oxide; etc.

For the purposes of the present invention, the term “graphene” refers to pure or relatively pure carbon in the form of a relatively thin, nearly transparent sheet, which is one atom in thickness (i.e., a monolayer sheet of carbon), or comprising multiple layers (multilayer carbon sheets), having a plurality of interconnected hexagonal cells of carbon atoms which form a honeycomb like crystalline lattice structure. In addition to hexagonal cells, pentagonal and heptagonal cells (defects), versus hexagonal cells, may also be present in this crystal lattice.

For the purposes of the present invention, the term “functionalized graphene” refers to graphene which has incorporated into the graphene lattice a variety chemical functional groups such as —OH, —COOH, NH.sub.2, etc., in order to modify the properties of graphene.

For the purposes of the present invention, the term “graphene oxide” (also known as “graphitic acid” and “graphite oxide”) refers interchangeably to a compound of carbon, oxygen, and hydrogen which may exist in variable ratios of these three atoms, and which may be obtained by treating graphite with strong oxidizers.

For the purposes of the present invention, the term “partially reduced graphene oxide” refers to graphene oxide that, upon reduction, contains from about 5 about 30% oxygen by weight of the graphene oxide.

For the purposes of the present invention, the terms “graphene platelets” and “graphene sheets” refer interchangeably to platelets of graphene comprising one or more layers of a two-dimensional (2D) graphene plane, and may also refer to platelets and sheets comprised of graphene oxide, partially reduced graphene oxide, functionalized graphene, etc.

For the purposes of the present invention, the term “graphene nanoplatelets (NGPs)” and “nanosheets” refer interchangeably to platelets of graphene, and may also refer to platelets and sheets comprised of graphene oxide, partially reduced graphene oxide, functionalized graphene, etc., having a thickness in the range of from about 0.34 to about 100 nm.

For the purposes of the present invention, the term “graphene-like nanoplatelets” refers to graphene-like materials having platelet characteristics the same or similar to graphene nanoplatelets (NGPs).

For the purposes of the present invention, the term “flakes” refers to particles in which two of the dimensions (i.e., width and length) are significantly greater compared to the third dimension (i.e., thickness).

For the purposes of the present invention, the term “graphite flakes” refers to graphite material in the form of flakes.

For the purposes of the present invention, the term “powder” refers to a solid material which is comprised of a large number of fine particles.

For the purposes of the present invention, the term “film” refers to a relatively thin continuous layer of material, and which may be supported on or by other materials, or which may be unsupported on or by other materials.

For the purposes of the present invention, the term “solvent” refers to a liquid which may dissolve or suspend another material which may be a solid, gas, or liquid.

For the purposes of the present invention, the term “compatible solvent” refers to a solvent which may provide an effective medium for the formation of a solution or dispersion of one or more solutes without significant detrimental effects to the other components present in the solution or dispersion, e.g., is miscible.

For the purposes of the present invention, the term “high boiling solvent” refers to refers to a solvent which boils at or near a temperature of greater than about 100.degree. C. Suitable high boiling solvents for use herein may include, for example, one or more of: ethylene carbonate (EC); propylene carbonate (PC); diethyl carbonate (DEC); dimethyl carbonate (DMC); etc.

For the purposes of the present invention, the term “blend,” “blending,” and similar words and/or phrases refers to combining, mixing together, unifying, etc., a plurality of components, compounds, compositions, substances, materials, etc.

For the purposes of the present invention, the term “substantially uniformly dispersed” refers to a dispersion of a material, substance, compound, etc., in the bulk (continuous) phase (e.g., polymer) such that the bulk phase is substantially uniform in terms of composition, texture, characteristics, properties, etc.

For the purposes of the present invention, the term “structural support” refers to structures such as molds, forms, constructs, scaffolds, etc., which may provide permanent or temporary support in preparing three-dimensional objects, parts, etc.

For the purposes of the present invention, the term “solid” refers to refers to non-volatile, non-liquid components, compounds, materials, etc.

For the purposes of the present invention, the term “liquid” refers to a non-gaseous fluid components, compounds, materials, etc., which may be readily flowable at the temperature of use (e.g., room temperature) with little or no tendency to disperse and with a relatively high compressibility.

For the purposes of the present invention, the term “room temperature” refers to refers to the commonly accepted meaning of room temperature, i.e., an ambient temperature of from about 20.degree. to about 25.degree. C.

For the purposes of the present invention, the term “extrudable” refers to composites, composition, substance, material, etc., which is sufficiently malleable, pliable, thermoplastic, etc., such that it may be forced through an extrusion die to form, for example, filaments, threads, strands, fibers, films, pellets, etc.

For the purposes of the present invention, the term “fusible” refers to a thermoplastic composition, substance, material, etc., which may be fused, sintered, joined together, combined, etc., by the application of heat.

For the purposes of the present invention, the term “three-dimensional (3D) printable material” refers to a thermoplastic composition, substance, material, etc., which may be formed into a three-dimensional (3D) article, objects, parts, etc., by a three-dimensional (3D) printing technique.

For the purposes of the present invention, the term “three-dimensional (3D) printing” (also known as “additive printing” and “additive manufacturing”) refers to any of various processes, techniques, etc. (e.g., coating, spraying, depositing, applying, extruding, fusing, sintering, etc., or any combination thereof) for making a three-dimensional (3D) article, object, part, etc. from a three-dimensional (3D) model, other electronic data source, etc., through additive processes in which successive layers of material (e.g., filaments, films, powders, particles, pellets, etc.) may be laid down, for example, under computer control. Three-dimensional (3D) printing processes, techniques, etc., may include, for example, fused filament fabrication (FFF) (also referred to herein interchangeably as fused deposition modeling (FDM) and fused extrusion deposition (FED)), selective laser sintering (SLS) (also referred to herein interchangeably as selective laser melting (SLM)), inkjet head 3D printing (also referred to herein interchangeably as inkjet 3D printing), etc.

For the purposes of the present invention, the term “sacrificial support” refers to a temporary removable support, mold, scaffold, construct, etc., which may be used to support, shape, etc., the formation of another three-dimensional (3D) article, object, part, etc., by a three-dimensional (3D) printing technique, or other method.

For the purposes of the present invention, the term “vapor sensor” refers to an electronic sensor which senses gaseous or volatile compositions, components, etc., such as water vapor, hydrocarbon vapors, carbon dioxide or carbon monoxide, organochlorides, alcohols, etc., and which may be hazardous, flammable, etc.

For the purposes of the present invention, the term “comprising” means various compounds, components, ingredients, substances, materials, layers, steps, etc., may be conjointly employed in embodiments of the present invention. Accordingly, the term “comprising” encompasses the more restrictive terms “consisting essentially of” and “consisting of.”

For the purposes of the present invention, the terms “a” and “an” and similar phrases are to be interpreted as “at least one” and “one or more.” References to “an” embodiment in this disclosure are not necessarily to the same embodiment.

For the purposes of the present invention, the term “and/or” means that one or more of the various compositions, compounds, ingredients, components, elements, capabilities, steps, etc., may be employed in embodiments of the present invention.

Description

Manufacturing techniques such as fused filament fabrication (FFF) and related three-dimensional (3D) printing techniques may provide benefits in preparing prototypes of objects, parts, etc. FFF techniques involve extrusion of, for example, a thermoplastic filament through a nozzle onto a supporting base alongside or on the top of the same or a different material which may then be joined by heat and/or adhesion. Such FFF techniques may also use precise, computer-based controlled motion of the nozzle along three axes to thus allow layer by layer construction of a three-dimensional (3D) object.

In an FFF three-dimensional (3D) printing process, the polymer may be supplied to the extruder in form of filament, pellets, etc. The extruder may be kept at elevated temperatures sufficient to melt the polymer to form a softened or molten material. The softened or molten material is then pushed through extrusion orifice (die) under a force provided by a feeding mechanism. The temperature of the extruder, material feeding force, diameter of the extruder orifice and viscoelastic properties of the material determines the deposition rate of the extruded material. In an embodiment of a FFF printer, the diameter of the orifice of the extruder nozzle may be in the range of, for example, from about 0.3 to about 0.7 mm (e.g., around) 0.4 mm. The temperature of the extruder may be set, for example, in the range of from about 100.degree. to about 300.degree. C. (such as from about 150.degree. to about 250.degree. C.). During extrusion, the shear rate at the nozzle of the extruder may reach a value of, for example, 1000 1/sec, with the viscosity of the polymer melt in the extruder at this shear rate being about 1,200 Pa-sec.

FFF three-dimensional (3D) printing techniques differ from other three-dimensional (3D) printing in using a supportive structure, which may be retained or removed after the printed article is completed. (Other 3D printing methods may not have to use such supports.) The ability to use water-soluble thermoplastic composite materials (e.g., comprising water-soluble thermoplastic polymers) in the form of, for example, filaments, pellets, etc., may permit currently available FFF printers to form such supports. Such water-soluble thermoplastic materials may be altered (e.g., by chemically altering their structure, by using nanoscopic particulate processing aids, plasticizers, structural reinforcement materials, and/or other additives, etc.) to enable extrusion of such filaments under conventional conditions/settings used in such FFF printers. These water-soluble thermoplastic materials may be used alone for printing temporary (sacrificial) support structures such as molds, scaffolds, forms, constructs, etc., or may be co-printed together with other water-insoluble thermoplastic polymers by using printers employing multiple extruders, thus building the entire three-dimensional (3D) article in one continuous step. By using convenient post-processing, such as immersion/washing of the printed temporary (sacrificial) water-soluble support structure with water, the water soluble support structure which is not part of the final product may thus be easily removed.

For preparing printable water-soluble molds, scaffolds, forms, constructs, etc., soluble support materials previously available have included polyvinyl alcohol (PVA) and high impact polystyrene (HIPS) filaments. In the case of water-soluble molds, scaffolds, forms, constructs, etc., prepared from PVA filaments, significant soaking time in warm water and sometimes prolonged treatment in an ultrasonic bath may be required to remove the sacrificial PVA support structure, and even then it may not be possible to remove the sacrificial PVA support structure completely from minute cavities that may be desirable in a particular design. In the case of molds, scaffolds, forms, constructs, etc., prepared from HIPS filaments, the sacrificial HIPS support structure may have to be dissolved in limonene, making the use of sacrificial HIPS support structures inconvenient, as well as generating difficult to dispose of waste products.

Polyethylene oxide (PEO) polymers may provide an alternative material for preparing such sacrificial molds, scaffolds, forms, constructs, etc. PEO polymers may be non-toxic, biodegradable and readily water soluble at ambient temperature. For example, the immersion of such sacrificial support structures prepared from PEO polymers in water at ambient temperature may be sufficient for complete removal of the support structure from the remaining/residual three-dimensional (3D) article, object, part, etc., that is formed by using the water-soluble support structure.

However, higher molecular weight water-soluble PEO polymer resins may have very high melt viscosities, thus requiring higher temperatures and forces to make extrusion into filamentary forms feasible. Such higher temperatures required for these higher molecular weight water-soluble PEO polymer resins to have appropriate viscosities at shear rates attained in the extruder (as well as in the printer nozzle) may cause melt fracture and thermal degradation of these higher molecular weight PEO resins to occur, and thus potentially make them unfeasible for use in certain three-dimensional (3D) printing techniques. By contrast, lower molecular weight water-soluble PEO resins, which may exhibit appropriate melt viscosities as such temperatures, may not be processable into filamentary forms due to lower melt strength and lower melt elasticity.

Suitable materials for three-dimensional (3D) printing techniques may require certain viscoelastic properties, adjustment of the material's melt viscosity by chemical modification, and/or by inclusion of certain processing aids such as nanoscopic particulates, plasticizers, structural/reinforcement materials, etc. To obtain such suitable three-dimensional (3D) printable materials in embodiments of the present invention, a water-soluble thermoplastic polymer composite is provided which has a melt viscosity in the range of from about 100 to about 10,000 Pa-sec. (such as from about 1000 to about 5000 Pa-sec.) at a shear rate in the range of from about 1.times.10.sup.1 to about 1.times.10.sup.4 reciprocal seconds (such as from about 1.times.10.sup.1 to about 1.times.10.sup.3 reciprocal seconds). Embodiments of these water-soluble thermoplastic polymer composites according to the present invention having the indicated melt viscosities at these specified shear rates exhibit a melt strength and elasticity sufficient for preparing filaments, films, powders, pellets, etc., useful in various three-dimensional (3D) printing techniques, such as fused filament fabrication (FFF) techniques, selective laser sintering (SLS) techniques, inkjet 3D printing techniques, injection 3D molding techniques, etc.

In embodiments of the present invention, a water-soluble thermoplastic polymer composite is provided which includes a water-soluble PEO graft polymer which has a polyethylene oxide (PEO) polymer backbone (i.e., having an approximate molecular weight of at least about 4,000,000 g/mol., for example, from about 4,000,000 to about 8,000,000 g/mol., such as from about 6,750,000 to about 7,250,000 g/mol.). Engrafted onto this polyethylene oxide polymer backbone is one or more polar vinyl monomers such as, for example, 2-hydroxyethyl methacrylate (HEMA), poly(ethylene glycol)methacrylate (PEG-MA), etc. The amount of the polar vinyl monomer which may grafted onto this polyethylene oxide (PEO) polymer backbone may be in the range from about 0.05 to about 10% (such as from about 0.1 to about 5%) by weight of the PEO polymer backbone. (The use of lower molecular weights polar vinyl monomers such as HEMA and lower molecular weight PEG-MAs tend encourage faster grafting reactions.)

Such grafting of polar vinyl monomers onto this PEO polymer backbone may be initiated and propagated by catalyzed thermal (heat) activation through the use of thermal catalytic initiators to generate free radicals upon exposure of the monomers to elevated temperatures. (The amount of heat which may be needed for radical formation may be specific to the particular initiator used and would understood by those skilled in the polymerization art.) A wide range of compounds containing O—O, S—S or N.dbd.N bonds may be employed as such thermal initiators, for example, alkyl, dialkyl, diaryl, arylalkyl peroxides, such as t-butyl peroxide, di-t-butyl peroxide, cumyl peroxide, 1,1-di-t-butylperoxy)hexane; acyl peroxides, such as acetyl peroxides and benzoyl peroxides; hydroperoxides such as cumyl hydroperoxide, p-methane hydroperoxide etc.; peresters and peroxyesters such as t-butyl peroxypivalate, t-butyl perbenzoateetc.; alkylsulfonyl peroxides; dialkyl peroxymonocarbonates; dialkyl peroxycarbonates; ketone peroxides; azo compounds, such as 2,2′-azobisisobutyronitrile (AIBN), 1,1′-azobis(cyclohexanecarbonitrile); etc. Such catalyzed thermal activation grafting reactions may be carried out in a variety of reaction vessels or devices which enable controlled uniform heating and mixing of the contents, including, for example, single and double screw extruders (e.g., counter-rotating twin screw extruders), such as Helicone mixers, Brabender plasticorders, Haake extruders (Haake, Paramus, N.J.), co-rotating, twin-screw extruders such as ZSK-30 twin-screw extruders (Werner & Pfleiderer Corp, Ramsey, N.J.), as well as similar mixing devices.

In one such embodiment for preparing the PEO grafted polymer, a PEO polymer resin (e.g., PEO WSR 303) may be placed in a petri dish and the temperature raised to 180.degree. C. while continuously mixing the PEO resin until a uniform melt is obtained. The polar vinyl monomer (e.g., HEMA at a weight ratio to the PEO resin of 1:20, or 5% by weight of the PEO resin) may then introduced and the resulting melt further mixed to insure uniform distribution (e.g., for 10 min.). Subsequently, a thermal initiator (e.g., 2,5-dimethyl-2,5-di(t-butylperoxy)hexane in a 1:20 weight ratio of initiator:HEMA) may added and the resulting mixture stirred at an elevated temperature of 180.degree. C. for 40 min. to ensure completion of the reaction. The resulting molten mixture comprising predominantly grafted PEO polymer may then be unloaded, cooled, crushed and stored in a desiccator before further processing.

In some embodiments of the present invention, the water-soluble thermoplastic polymer composite may further include one or more nanoscopic particulate processing aids substantially uniformly dispersed in the PEO graft polymer, such as titanium dioxide (TiO.sub.2) nanopowder, silica (SiO.sub.2) nanopowder, alumina (Al.sub.2O.sub.3) nanopowder, fumed silica, nanopowders of other metal oxides such as zirconia, vanadia, chromia, antimony oxide, tin oxide, ceria, zinc oxide, etc., surface-modified nanoscopic particulates (e.g., surface-modified nanopowders), etc. The amount of nanoscopic particulate processing aids included may be in an amount of, for example, from about 0.05 to about 10% by weight of the polymer composite, such as from about 0.1 to about 5% by weight of the polymer composite. Such compositions may further optionally include one or more plasticizers in an amount of from about 0.1 to about 10% by weight of the polymer composite, such as from about 1 to about 5% by weight of the polymer composite.

In other embodiments of the present invention, the water-soluble thermoplastic polymer composite may include one or more structural reinforcement materials substantially uniformly dispersed in the PEO graft polymer such as carbon fibers, glass fibers, metal or metal oxide fibers, clay; talc, chalk, boron nitride, magnesium hydroxide, magnesium carbonate, diatomaceous earth, mica, glass quartz, ceramic and/or glass microbeads, spheres, etc., graphene, graphene nanoplatelets, graphene oxide, reduced graphene oxide, functionalized graphene, graphite, carbon black, etc., as well as one or more plasticizers substantially uniformly dispersed in the polymer composite such as triethyl citrate, triacetin, propylene glycol, dibutyl sebacate, glycerol monostearate, diethyl phthalate, crown ethers, etc. The amount of the one or more structural reinforcement materials included in may be from about 0.1 to about 20% by weight of the polymer composite, such as from about 5 to about 15% by weight of the polymer composite. The amount of the one or more plasticizers included in may be from about 0.1 to about 15% by weight of the polymer composite, such as from about 5 to about 10% by weight of the polymer composite. Such water-soluble thermoplastic polymer composites may further optionally include one or more high boiling solvents such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), etc. In some embodiments of the present invention, and in addition to these structural reinforcement materials, these water-soluble thermoplastic polymer composites may also include the aforementioned nanoscopic particulate processing aids.

The benefits in terms of melt viscosity, as well as other properties, of these water-soluble thermoplastic polymer composite compositions are illustrated by the graphical plots shown in FIGS. 1 and 2 . FIG. 1 represents a graphical plot, indicated as 100, of three different compositions as function of melt viscosity versus shear rate: (a) a polyethylene oxide (PEO) polymer (WSR 303, approximate molecular weight 7,000,000 g./mol.) as the neat (unmodified) polymer, indicated by curve 104; (b) the same PEO polymer but having grafted thereon 5% 2-hydroxyethyl methacrylate (HEMA), indicated by curve 108; and (c) the PEO HEMA grafted polymer to which has been added plasticizer (i.e., poly(ethylene glycol) dimethylether in amount of 9.5% by weight the polymer composite composition) and nanoscopic particulate titanium dioxide (in an amount of 4.5% by weight the polymer composite composition) as processing aids to form the polymer composite composition, indicated by curve 112. As shown by curve 104, the neat PEO polymer has a relatively high melt viscosity which decreases essentially linearly as the shear rate increases, i.e., the melt viscosity is highly dependent on the shear rate. As shown by curve 108, the PEO HEMA grafted polymer has a much lower melt viscosity compared to that of the neat PEO polymer which is somewhat but less dependent on the shear rate. As shown by curve 112, the inclusion of the nanoscopic particulate titanium dioxide processing aid and plasticizer further lowers the melt viscosity which is even less dependent on the shear rate compared to the PEO HEMA grafted polymer only.

FIG. 2 represents a graphical plot, indicated as 200, of the PEO HEMA grafted polymer only of FIG. 1 , as well as the PEO HEMA grafted polymer to which is added the plasticizer and nanoscopic particulate titanium dioxide processing aid of FIG. 1 to form the polymer composite composition. The respective melt viscosity versus temperature curves for the respective compositions are indicated as 208 for the PEO HEMA grafted polymer only, and as 212 for the PEO HEMA grafted polymer to which has been added the nanoscopic particulate processing aids and plasticizer. As shown by curves 208 and 212, the melt viscosity of the PEO HEMA grafted polymer only is relatively higher and less sensitive to increases in temperature compared to the PEO HEMA grafted polymer to which has been added the processing aids.

Embodiments of these water-soluble thermoplastic polymer composites of the present invention may be prepared by dissolving/suspending the PEO grafted polymer in a solvent (such as water, acetonitrile, etc.), along with the nanoscopic particulate processing aids, plasticizers, structural reinforcement materials, etc. In one such embodiment, a PEO grafted polymer may be dissolved in, for example, acetonitrile and a titanium dioxide nanopowder, along with poly(ethylene glycol) dimethyl ether (as the plasticizer) may be added. The amount of titanium dioxide nanopowder added may be in the range of from about 0.1 to about 20% (such as in the range of from about 5 to about 10%) by weight the polymer composite. The amount of plasticizer (which may be optionally included) added may be in the range of from about 0.1 to about 10% (such as in the range of from about 1 to about 10%) by weight the polymer composite. The resulting mixture may then be sonicated in ultrasonic bath for several hours to ensure complete dissolution of the PEO grafted polymer, as well as uniform distribution/dispersion of nanoscopic titanium dioxide powder/plasticizer. The resulting slurry may be poured into a tray and the solvent removed/allowed to evaporate, such as by a rotatory evaporator, etc. Upon removal of solvent the resulting polymer composite may be chopped up and stored in a container with a desiccant for subsequent processing.

In some embodiments, the solvent may be omitted and, after completion of the grafting reaction to form the PEO graft polymer, the remaining components such as the nanoscopic particulate processing aid, plasticizer, structural reinforcement materials, etc., may be directly introduced into a heated reaction vessel (such as Helicone mixer, Brabender plasticorder and similar heated reaction vessels capable of adequate heating and mixing melts) further modifying the PEO graft polymer in “one pot.” The resulting thermoplastic polymer composite may then be poured into a tray, cooled, chopped and extruded, or may introduced as a molten thermoplastic polymer composite directly into the hopper of the extruder if faster processing is desired. In other embodiments, the compounding of the thermoplastic (extrudable) polymer composite may be achieved directly in an extruder that is used for filament production. The single and double screw extruders may be employed, with a double screw extruder to provide a more homogeneous distribution of the components in the molten bulk polymer composite.

In one embodiment, a water-soluble thermoplastic polymer composite comprising the PEO grafted polymer, nanoscopic particulate processing aid, optionally including a plasticizer, or comprising the PEO grafted polymer, structural reinforcement materials (e.g., carbon fibers, glass fibers, etc.), and plasticizer may be extruded on a Filabot extruder to provide a uniform filament having a diameter of 1.75 mm in diameter that may be air cooled and wound up on the spool.

Embodiments of the water-soluble thermoplastic polymer composites of the present invention may be extruded into filaments, films, etc., to provide, for example, sacrificial supports such as, casting molds, biological sacrificial supports, etc., by using, for example, FFF printers. These water-soluble thermoplastic polymer composites of the present invention may be used to just print such temporary (sacrificial) support structures such as molds, scaffolds, forms, constructs, etc., or may be co-printed together with other water-insoluble thermoplastic polymers (e.g., polyethylenes, polypropylenes, polystyrenes, polyamides such as nylon, polyurethanes, polyvinyl acetates, polyacrylates, polymethacrylates, polyesters, etc.) by using FFF printers employing multiple extruders, thus creating the desired three-dimensional (3D) article, object, part, etc., in one step. The sacrificial support structure co-printed with the water-insoluble thermoplastic polymer to form a water-insoluble three-dimensional article, object, part, etc., may then be removed (dissolved), for example, by immersion in water, rinsing, etc., to thus leave behind the intact three-dimensional (3D) article, object, part, etc., made from the water-insoluble thermoplastic polymer.

Embodiments of the water-soluble thermoplastic polymer composites of the present invention may also be extruded into filaments which have a plurality of segments wherein each pair of adjacent segments have at least one different feature and are arranged in a specific order. With such a filament, a fused filament fabrication (FFF) printer may carry out a pattern of printing which is synchronized with the order of the segments in such a filament to provide specified three-dimensional (3D) articles. See PCT Appln No. PCT/US15/11878 (Graphene 3d Lab Inc.), filed Jan. 17, 2015, the entire disclosure and contents of which is herein incorporated by reference, which describes such filaments, the preparation of such filaments, and the use of such filaments in fused filament fabrication (FFF) printer.

Embodiments of the present invention may also include preparing vapor sensors from these water-soluble thermoplastic polymer composites by such three-dimensional (3D) printing techniques. In preparing vapor sensors according to some embodiments, the structural/functional reinforcement materials may comprise a graphene-like material (e.g., one or more of functionalized or plasma treated graphene nanoplatelets; reduced or partially reduced graphene oxide; carbon fibers; carbon nanotubes; carbon black, etc.). For example, initially 4,4′-azobis(4-cyanopentanoyl dichloride) may be polycondensed with a different portion of the PEO polymer having terminal hydroxyl groups. The resulting polycondensed azo-PEO polymer may then be heated in the presence of the graphene-like material to cause decomposition, thus yielding nitrogen gas and PEO polymer radicals which may be trapped on the surface of the graphene-like material, thus forming graphene-like materials fractionally (i.e., randomly, sporadically, etc.) coated with PEO polymer. These graphene-like materials fractionally coated with PEO polymer may be subsequently combined with bulk PEO grafted polymer, plasticizer, and nanoscopic particulate processing aids to form the water-soluble thermoplastic polymer composite. This water-soluble thermoplastic polymer composite may then extruded, yielding filaments which may be used to print a vapor sensor by, for example, fused filament fabrication techniques. These filaments may also be pelletized, crushed or formed into powders for use in injection molding (3D) printing techniques. Alternatively, this water-soluble thermoplastic polymer composite may be formed into pellets, films, powders, etc., or may be suspended in a compatible solvent (such as acetonitrile, ethanol, etc.) and then used to ink-jet (3D) print such vapor sensors. In another embodiment, a vapor sensor filament may be obtained by a reactive extrusion wherein the azo-polymer (i.e., 4,4′-azobis(4-cyanopentanoyl dichloride) polycondensed with PEO polymer, as described above), may be introduced into the extruder along with the bulk PEO grafted polymer, graphene-like material, plasticizer, nanoscopic particulate processing aid, etc. Upon heating in the extruder, the polycondensed azo-PEO polymer may again be decomposed to form PEO polymer radicals which again may be trapped by the surface of the graphene material, thus yielding graphene-like materials fractionally coated with PEO polymer which are then substantially uniformly distributed in the bulk PEO grafted polymer composite to provide a vapor sensor-forming composition at the extruder exit. The electrical resistance of such composite may be increased, compared to the initial resistance, by exposure to solvent vapors of, for example, dichloromethane, chloroform, tetrahydrofuran, carbon tetrachloride, acetonitrile, alcohols, cyclohexane, etc., thus providing a signaling sensory output. The initial resistance of the composite that has been exposed to such solvent vapors may be substantially reestablished by subsequent exposure thereof to dry air. Such reversibility of electrical resistance may allow for multiple cycles of operation of a vapor sensor printed with such composites.

This application may incorporate material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of this application or any portion of this disclosure, as it appears in the Patent and Trademark Office patent/patent application file or records, for the limited purposes required by law, but otherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should be understood that they have been presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant art(s) that various changes in form and detail can be made therein without departing from the spirit and scope. In fact, after reading the above description, it will be apparent to one skilled in the relevant art(s) how to implement alternative embodiments. Thus, the scope of the present invention should not be limited by any of the above described exemplary embodiments.

In addition, it should also be understood that any figures in the drawings that highlight any functionality and/or advantages, are presented herein for illustrative purposes only. The disclosed architecture is sufficiently flexible and configurable, such that it may be utilized in ways other than those that may be shown. For example, the steps listed in any flowchart may be re-ordered or only optionally used in some embodiments.

Further, the purpose of the Abstract of the Disclosure in this application is to enable the U.S. Patent and Trademark Office, as well as the public generally, including any scientists, engineers and practitioners in the art who are not familiar with patent or other legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. Accordingly, while the Abstract of the Disclosure may be used to provide enablement for the following claims, it is not intended to be limiting as to the scope of those claims in any way.

Finally, it is the applicants' intent that only claims that include the express language “means for” or “step for” be interpreted under 35 U.S.C. .sctn. 112, paragraph 6. Claims that do not expressly include the phrase “means for” or “step for” are not to be interpreted as being within the purview of 35 U.S.C. .sctn. 112, paragraph 6.

Some of the illustrative aspects of the present invention may be advantageous in solving the problems herein described and other problems not discussed which are discoverable by a skilled artisan.

While the above description contains much specificity, these should not be construed as limitations on the scope of any embodiment, but as exemplifications of the presented embodiments thereof. Many other ramifications and variations are possible within the teachings of the various embodiments. While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best or only mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.

Thus the scope of the invention should be determined by the appended claims and their legal equivalents, and not by the examples given.

The claims in the instant application are different than those of the parent application or other related applications. Applicant therefore rescinds any disclaimer of claim scope made in the parent application or any predecessor application in relation to the instant application. Any such previous disclaimer and the cited references that it was made to avoid, may need to be revisited. Further, any disclaimer made in the instant application should not be read into or against the parent application. 

What is claimed is:
 1. A method for preparing a vapor sensitive sacrificial support material comprising: decomposing a polycondensed PEO polymer with heat in the presence of a graphene-like material to release PEO polymer radicals from the polycondensed PEO polymer, wherein at least a portion of the PEO polymer radicals become trapped on at least a portion of a surface of the graphene-like material to form a coated graphene-like material, defined as a structural reinforcement material; forming the vapor sensitive water-soluble thermoplastic polyethylene oxide graft polymer comprising: a polyethylene oxide polymer backbone; and from about 0.05% to about 10% by weight of the polyethylene oxide polymer backbone of at least one polar vinyl monomer grafted to the polyethylene oxide polymer backbone; and one or more nanoscopic particulate processing aids uniformly dispersed in the graft polymer in an amount of from about 0.05 to about 10% by weight of the vapor sensitive water-soluble thermoplastic polymer composite; wherein the structural reinforcement material is uniformly dispersed in the vapor sensitive water-soluble thermoplastic polymer composite in an amount of from about 0.1 to about 20% by weight of the vapor sensitive water-soluble thermoplastic polymer composite.
 2. The method of claim 1, wherein the vapor sensitive water-soluble thermoplastic polymer composite is formable into a 3D printable sacrificial support material.
 3. The method of claim 1, wherein the vapor sensitive water-soluble thermoplastic polyethylene oxide graft polymer composite has a viscosity in the range of about 100 to about 10,000 Pa-sec. when measured at a shear rate in the range of about 1×10¹ to about 1×10⁴ reciprocal seconds.
 4. The method of claim 1, wherein water-soluble is defined as at least one of a composite, composition, substance, and material that is soluble in that it melts, liquefies, dissolves, disintegrates, falls apart, or solubilizes when brought into contact with an aqueous fluid.
 5. The method of claim 1, wherein the vapor sensitive water-soluble thermoplastic polymer composite has an initial electrical resistance value that increases when the vapor sensitive water-soluble thermoplastic polymer composite is exposed to solvent vapor.
 6. The method of claim 5, wherein the solvent vapor comprises at least one of dichloromethane, chloroform, tetrahydrofuran, carbon tetrachloride, acetonitrile, alcohols, and cyclohexane.
 7. The method of claim 5, wherein the electrical resistance of the vapor sensitive water-soluble thermoplastic polymer composite returns to the initial electrical resistance value when the vapor sensitive water-soluble thermoplastic polymer composite is exposed to dry air.
 8. The method of claim 2, wherein the 3D printable sacrificial support material is in the form of a filament, film, powder, pellet, or suspended in solvent.
 9. The method of claim 1, wherein the graphene-like material comprises at least one of graphene, graphene nanoplatelets, graphene oxide, graphite, functionalized graphene nanoplatelets, plasma treated graphene nanoplatelets; reduced graphene oxide, partially reduced graphene oxide, carbon fibers, carbon nanotubes, and carbon black.
 10. The method of claim 1, wherein the catalytic thermal initiator comprises at least one of 4,4′-azobis (4-cyanopentanoyl dichloride), alkyl, dialkyl, diaryl, arylalkyl peroxides, di-t-butyl peroxide, cumyl peroxide, 1,1-di-t-butylperoxy, hexane, acyl peroxide, acetyl peroxide, benzoyl peroxide, hydroperoxide, cumyl hydroperoxide, p-methane hydroperoxide, perester, peroxyester, t-butyl peroxypivalate, t-butyl perbenzoateetc, alkylsulfonyl peroxide, dialkyl peroxymonocarbonate, dialkyl peroxycarbonate, ketone peroxide, azo compound, 2,2′-azobisisobutyronitrile (AIBN), and 1,1′-azobis (cyclohexanecarbonitrile).
 11. The method of claim 2, wherein the 3D printable sacrificial support material is at least one of a filament for a fused filament fabrication (FFF) technique, a powder or pellet for a selective laser sintering (SLS) technique, is suspended in a solvent for an inkjet 3D printing technique, and a pellet, powder, or crushed for an injection molding 3D printing technique.
 12. The method of claim 1, wherein the one or more nanoscopic particulate processing aids comprise at least one of titanium dioxide nanopowder, alumina nanopowder, silica nanopowder, fumed silica, zirconia nanopowder, vanadia nanopowder, antimony oxide nanopowder, tin oxide nanopowder, ceria nanopowder, and zinc oxide nanopowder.
 13. The method of claim 1, wherein the vapor sensitive water-soluble thermoplastic polymer composite includes at least one plasticizer in an amount of from about 0.1 to about 10% by weight of the vapor sensitive water-soluble thermoplastic polymer composite.
 14. A 3D printable sacrificial support material for use in printing a 3D article, the 3D printable sacrificial support material comprising: a vapor sensitive water-soluble thermoplastic polymer composite comprising: a vapor sensitive water-soluble thermoplastic polyethylene oxide graft polymer having: a polyethylene oxide polymer backbone; and from about 0.05% to about 10% by weight of the polyethylene oxide polymer backbone of at least one polar vinyl monomer grafted to the polyethylene oxide polymer backbone; one or more nanoscopic particulate processing aids uniformly dispersed in the graft polymer in an amount of from about 0.05 to about 10% by weight of the vapor sensitive water-soluble thermoplastic polymer composite; at least one plasticizer in an amount of from about 0.1 to about 10% by weight of the vapor sensitive water-soluble thermoplastic polymer composite; and a structural reinforcement material uniformly dispersed in the vapor sensitive water-soluble thermoplastic polymer composite in an amount of from about 0.1 to about 20% by weight of the vapor sensitive water-soluble thermoplastic polymer composite; wherein the structural reinforcement material comprises a graphene-like material that includes polycondensed polyethylene oxide polymer radicals carried on at least a portion of a surface of the graphene-like material; and wherein the vapor sensitive water-soluble thermoplastic polymer composite has an initial electrical resistance value that increases when the vapor sensitive water-soluble thermoplastic polymer composite is exposed to solvent vapor; wherein the electrical resistance of the vapor sensitive water-soluble thermoplastic polymer composite return to the initial electrical resistance value when the vapor sensitive water-soluble thermoplastic polymer composite is exposed to dry air; and wherein water-soluble is defined as at least one of a composite, composition, substance, and material that is soluble in that it melts, liquefies, dissolves, disintegrates, falls apart, or solubilizes when brought into contact with an aqueous fluid.
 15. The 3D printable sacrificial support material of claim 14, wherein the vapor sensitive water-soluble thermoplastic polymer composite has a viscosity in the range of about 100 to about 10,000 Pa-sec. when measured at a shear rate in the range of about 1×10¹ to about 1×10⁴ reciprocal seconds.
 16. The 3D printable sacrificial support material of claim 14, wherein the solvent vapor comprises at least one of dichloromethane, chloroform, tetrahydrofuran, carbon tetrachloride, acetonitrile, alcohols, and cyclohexane.
 17. The 3D printable sacrificial support material of claim 14, wherein the 3D printable sacrificial support material is in the form of a filament, film, powder, pellet, or suspended in solvent.
 18. The 3D printable sacrificial support material of claim 14, wherein the graphene-like material comprises at least one of graphene, graphene nanoplatelets, graphene oxide, graphite, functionalized graphene nanoplatelets, plasma treated graphene nanoplatelets; reduced graphene oxide, partially reduced graphene oxide, carbon fibers, carbon nanotubes, and carbon black.
 19. The 3D printable sacrificial support material of claim 14, wherein the 3D printable sacrificial support material is at least one of a filament for a fused filament fabrication (FFF) technique, a powder or pellet for a selective laser sintering (SLS) technique, is suspended in a solvent for an inkjet 3D printing technique, and a pellet, powder, or crushed for an injection molding 3D printing technique.
 20. The 3D printable sacrificial support material of claim 14, wherein the one or more nanoscopic particulate processing aids comprise at least one of titanium dioxide nanopowder, alumina nanopowder, silica nanopowder, fumed silica, zirconia nanopowder, vanadia nanopowder, antimony oxide nanopowder, tin oxide nanopowder, ceria nanopowder, and zinc oxide nanopowder. 